Modelling the effects of physical–biological interactions and spatial variability in spawning and nursery areas on transport and retention of sardine Sardinops sagax eggs and larvae in the southern Benguela ecosystem

2006 ◽  
Vol 61 (3-4) ◽  
pp. 212-229 ◽  
Author(s):  
David C.M. Miller ◽  
Coleen L. Moloney ◽  
Carl D. van der Lingen ◽  
Christophe Lett ◽  
Christian Mullon ◽  
...  
Keyword(s):  
Spatial Variability ◽  
Biological Interactions ◽  
Nursery Areas ◽  
Sardinops Sagax ◽  
Eggs And Larvae

Vertical distribution of pilchard (Sardinops sagax) eggs and larvae off Southern Australia

1999 ◽  
Vol 50 (2) ◽  
pp. 117 ◽  
Author(s):  
W. J. Fletcher
Keyword(s):  
Vertical Distribution ◽  
Accurate Estimation ◽  
Relative Depth ◽  
Sardinops Sagax ◽  
Bottom Depth ◽  
Shelf Region ◽  
Opening And Closing ◽  
Egg Stages ◽  
Eggs And Larvae ◽  
Egg Abundance

Plankton samples were obtained from four to six discrete depths at 33 stations in July 1994 by using the ‘EZ’ multiple opening and closing net during a cruise along the shelf region from Adelaide to Albany, southern Australia. At the 19 stations (88 tows) where pilchard eggs were common, recently spawned eggs were most abundant at depths of 40–60 m, or 60% of total bottom depth. Most older egg stages were found closer to, or at, the surface. During day-time, most pilchard larvae were caught at the surface. At night, pilchard larvae appeared to spread out, with lower overall rates of capture but a bigger proportion caught below the surface. The effects of these changes in relative depth with age are discussed in relation to the accurate estimation pilchard egg abundance for biomass calculations.

Spatial distribution of sardine (Sardinops sagax) eggs and larvae: an application of geostatistics and resampling to survey data

1999 ◽  
Vol 56 (6) ◽  
pp. 907-914 ◽  
Author(s):  
W J Fletcher ◽  
Neil R Sumner
Keyword(s):  
Spatial Distribution ◽  
Survey Data ◽  
Ordinary Kriging ◽  
Sampling Design ◽  
Optimal Sampling ◽  
Bootstrap Resampling ◽  
Two Dimensional ◽  
Optimal Sampling Design ◽  
Sardinops Sagax ◽  
Eggs And Larvae

The abundance of eggs and larvae of sardine (pilchard) (Sardinops sagax) off the south coast of Western Australia was investigated using geostatistical and bootstrap resampling techniques. A two-dimensional correlogram showed that the patch of newly spawned pilchard eggs had dimensions of 8 nautical miles (M) in diameter in the offshore direction and 10 M in the alongshore direction. For older stages, the size of the patch tended to increase and the level of cohesion decrease. It was more difficult to determine the size of the patch from directional variograms. The abundance of 1- and 2-day-old eggs in the study area was estimated using ordinary kriging. A bootstrapping analysis suggested that the optimal sampling design for day 1 eggs should use 4 × 10 M grids, an increase in intensity on the 5 × 15 M grids used in previous surveys.

scholarly journals Spatial variability in the icthyoplankton structure of a subtropicalhypersaline lagoon

2016 ◽  
Vol 64 (2) ◽  
pp. 149-156 ◽  
Author(s):  
Judson da Cruz Lopes da Rosa ◽  
Mariana Dantas Alberto ◽  
Wanda Maria Monteiro Ribas ◽  
Maria Helena Campos Baeta Neves ◽  
Lohengrin Dias de A. Fernandes
Keyword(s):  
Spatial Variability ◽  
Fish Species ◽  
Environmental Conditions ◽  
Environmental Changes ◽  
High Salinity ◽  
Fish Larvae ◽  
Reproductive Season ◽  
Uneven Distribution ◽  
Eggs And Larvae ◽  
Spatial And Temporal Analyses

Abstract The Lagoa de Araruama is a hypersaline ecosystem inhabited by distinct fish species, either permanently or during their reproductive season. Over recent years, some significant environmental changes have been observed in this ecosystem related to the sewage runoff, as salinity decrease (from 64 to 41 psu during the last 40 years) and nutrients increase. As both changes are thought to affect the ichthyoplankton assemblage, the present study aimed to evaluate all the potential relationships between salinity disruption and fish larvae distribution. Ichtyoplankton samples were collected monthly from January 2010 to March 2011 at eight sites in Araruama Lagoon by means of a WP2 plankton net equipped with a flowmeter. During this period, low egg densities were coincident with high salinity regions, suggesting that adults are avoiding to release their eggs under less favorable environmental conditions to the larvae. The uneven distribution of eggs and larvae inside the lagoon, as revealed by both spatial and temporal analyses lead us to suggest that changes in salinity have influenced the reproductive rhythms of those fish species that depend upon the Lagoa de Araruama.

scholarly journals Cod’s Journey Back Home—From Birth to Nursery

2021 ◽  
Vol 9 ◽  
Author(s):  
Clarissa Akemi Kajiya Endo ◽  
Frode B. Vikebø ◽  
Natalia A. Yaragina ◽  
Solfrid Sætre Hjøllo ◽  
Leif Christian Stige
Keyword(s):  
Yolk Sac ◽  
Living Conditions ◽  
Ocean Currents ◽  
Adult Fish ◽  
Ocean Water ◽  
Nursery Areas ◽  
Food Reserve ◽  
Eggs And Larvae

Adult cod swim hundreds of kilometers away from home to release their eggs into the ocean water. After some days, tiny larvae hatch from the eggs. At first, the larvae have a small food reserve to sustain them during their first days of life. Soon after emptying the yolk-sac, the larvae must find food on their own. Both eggs and larvae are carried by the ocean currents and they experience large changes in conditions as they drift back to the nursery areas where their parents came from, where the larvae grow up to become adult fish. Our research on cod indicates that the number and location of cod larvae are associated with the size of the spawning adults; and that the number of larvae influences how many cod will grow to be recruits. So, it is important to also know the living conditions of the parents before they spawn, which will be important for the survival of their offspring.

Distribution and timing of spawning by the Australian pilchard (Sardinops sagax neopilchardus) off Albany, Western Australia

1992 ◽  
Vol 43 (6) ◽  
pp. 1437 ◽  
Author(s):  
WJ Fletcher ◽  
RJ Tregonning
Keyword(s):  
Continental Shelf ◽  
Western Australia ◽  
Outer Shelf ◽  
Spawning Activity ◽  
Leeuwin Current ◽  
Sardinops Sagax ◽  
Marine Embayment ◽  
Eggs And Larvae ◽  
Main Influence ◽  
Timing Of Spawning

The pattern of abundance of eggs and larvae of the Australian pilchard, Sardinops sagax neopilchardus, collected by plankton tows in the region off Albany, Western Australia, was investigated. In 1989, surface tows were undertaken at five localities extending from the marine embayment of Princess Royal Harbour to the continental shelf just outside King George Sound. In 1990, oblique tows were undertaken at six localities extending from just inside King George Sound to beyond the edge of the continental shelf. Eggs and larvae of pilchards were found in many months, but peaks in egg numbers were found in July and December of both 1989 and 1990. There was, however, only one peak in larva abundance, during December. Most eggs and larvae were found in the region 2-8 km offshore from the entrance to King George Sound. Few were found either well inside King George Sound and Princess Royal Harbour or in outer-shelf localities. Spawning in the Albany region therefore occurred inshore of the main influence of the eastward-flowing tropical waters of the Leeuwin Current. The implications of this spawning activity in relation to the fishery for this species and the potential for stock separation along this coast are discussed.

Dispersion of vendace eggs and larvae around potential nursery areas reveals their reproductive strategy

2019 ◽  
Vol 64 (5) ◽  
pp. 843-855 ◽  
Author(s):  
Juha Karjalainen ◽  
Janne Juntunen ◽  
Tapio Keskinen ◽  
Saija Koljonen ◽  
Kristiina Nyholm ◽  
...  
Keyword(s):  
Reproductive Strategy ◽  
Nursery Areas ◽  
Eggs And Larvae

Egg and larval abundance and spawning localities of the anchovy (Engraulis australis) and pilchard (Sardinops neopilchardus) near Phillip Island, Victoria

1995 ◽  
Vol 46 (4) ◽  
pp. 735 ◽  
Author(s):  
FE Hoedt ◽  
WF Dimmlich
Keyword(s):  
Spatial Variability ◽  
Larval Abundance ◽  
Adult Fish ◽  
Spawning Area ◽  
Fish Spawning ◽  
The Mean ◽  
Eggs And Larvae

The distribution and abundance of the eggs and larvae of the anchovy (Engraulis australis) and pilchard (Sardinops neopilchardus) were determined for the waters near Phillip Island between May 1992 and January 1994. Eggs and larvae of both species were common in these waters, indicating that this region is an important spawning area for both species. Pilchard eggs and larvae occurred at sample stations in Bass Strait and in the western entrance to Western Port. Anchovy eggs and larvae were collected both within Western Port and at most plankton stations in Bass Strait. The mean density of anchovy eggs in Western Port differed markedly between the two spawning seasons, suggesting that the number of adult fish spawning therein can vary between years. Densities of pilchard eggs and of the larvae of both species exhibited considerable spatial variability in Bass Strait.

Tailor (Pomatomus saltatrix) off Western Australia: where does it Spawn and how are the Larvae Distributed?

1996 ◽  
Vol 47 (2) ◽  
pp. 337 ◽  
Author(s):  
RC Lenanton ◽  
SG Ayvazian ◽  
AF Pearce ◽  
RA Steckis ◽  
GC Young
Keyword(s):  
Western Australia ◽  
Coastal Currents ◽  
Pomatomus Saltatrix ◽  
Inner Shelf ◽  
Spawning Period ◽  
Nursery Areas ◽  
Eggs And Larvae ◽  
Timing Of Spawning

Tailor is a key finfish resource in Western Australia and is heavily exploited, but there has been no information either on the location and timing of spawning of the species in these waters or on the subsequent distribution and movements of the larvae. The present study has reviewed the literature to elucidate where tailor typically spawn and in which salinities and water temperatures they are most likely to be found. These data have then been collated with new data on the biology of juvenile and adult tailor in Western Australia, and on the salinities, temperatures and water movements off the coast. This has enabled a hypothesis to be developed delineating where spawning is likely to occur in this region and where the larvae are distributed. It is proposed that spawning occurs in inner-shelf waters between spring and autumn. Eggs and larvae are most likely to be transported to coastal nursery areas by wind-driven northward coastal currents that predominate during the main spawning period.

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